Some features of changes in floras' richness in subtaiga forests on the east of European Russia

The analisys of spatial heterogenity of floras' reachness in Middle Volga and Priuralie regions results in the finding of biomes' boundaries. The identified maximums of floristic reachness appear to be confined to the boundaries previously proposed by different schemes of natural regionataation. The influence of landscape heterogenity on the floristic readiness' distribution is noted.